Folly is a noun that means "foolish or crazy behavior." It would be folly to spend all night playing video games when you have a difficult exam the next day.

Folly comes from the Old French word folie meaning "madness, stupidity." It can describe the silly or nonsensical things you do, like the folly of trying to rush across town in the middle of a snowstorm. Or it can describe the trait that makes people act that way: the folly of an inexperienced driver who doesn't know you can't speed on snow-covered roads. Can you see the word fool in folly? Not a coincidence.

Definitions of folly

n the trait of acting stupidly or rashly

foolishness, unwiseness
wisdom, wiseness
the trait of utilizing knowledge and experience with common sense and insight
indiscretion, injudiciousness
the trait of being injudicious
absurdity, fatuity, fatuousness, silliness
a ludicrous folly
the quality of being asinine; stupidity combined with stubbornness
Type of:
a distinguishing feature of your personal nature

n the quality of being rash and foolish

“trying to drive through a blizzard is the height of folly
craziness, foolishness, madness
Type of:
a poor ability to understand or to profit from experience

n foolish or senseless behavior

craziness, foolery, indulgence, lunacy, tomfoolery
meshugaas, mishegaas, mishegoss
(Yiddish) craziness; senseless behavior or activity
buffoonery, clowning, frivolity, harlequinade, japery, prank
acting like a clown or buffoon
schtick, schtik, shtick, shtik
(Yiddish) a prank or piece of clowning
Type of:
caper, frolic, gambol, play, romp
gay or light-hearted recreational activity for diversion or amusement

n a stupid mistake

betise, foolishness, imbecility, stupidity
Type of:
error, fault, mistake
a wrong action attributable to bad judgment or ignorance or inattention

Sign up, it's free!

Whether you're a student, an educator, or a lifelong learner, can put you on the path to systematic vocabulary improvement.